Biomedical Engineering Reference
In-Depth Information
Increase of luoride concentration drastically deteriorates the
corrosion resistance and dissolution rate signiicantly increases
(Fig. 5.17) [2]. Fluoride was found to dramatically increase the
corrosion current above a critical concentration of about 0.5 mM.
Figure 5.16
SEM images of NiTi wires in mixed solution of chloride and
luoride: (a) low magniication and (b) high magniication
[28].
Figure 5.17
Effect of luoride concentration on the dissolution rate of
Ti Grade 7 after potentiostatic polarization at 0 V SCE for
453 h (deaerated, 1M NaCl at 95°C) [2].
Brossia and Cragnolino added Pd (0.155%) to Ti [2]. Pd additions
increase the pitting and repassivation potentials in chloride
solutions, but Pd did signiicantly affect the localized corrosion
resistance of Ti. It was found that the Pd addition did not mitigate
the deleterious effects of luoride [2]. However, Nakagawa
et al
.
[31] reported that the Pt or Pd introduced to the Ti-alloy improves
the corrosion resistance of titanium in luoride solutions. They
